Recognition of self vs non-self by macrophages?
smori at nmsu.edu
Sun Nov 13 23:38:39 EST 1994
Ian A. York (york at mbcrr.dfci.harvard.edu) wrote:
: In article <39k5vf$70h at dns1.NMSU.Edu> smori at nmsu.edu (Shahram Mori) writes:
: >We all know that macrophages do not phagocytose everything that they come
: >across. If a free-flowing macrophage comes into contact with an antigen it
: >will pick it up. However it doesn't pick up 'normal' host cells that are
: >flowing in the blood. This would seem to require a way to differentiate
: >between the foreign and the self. It may be that there is also ( early in
: >development) pick up of self antigens but they go through the screening to
: >be removed just like T and B cells do early in life.
: It is true that macrophages do not phagocytose everything they
: come across. It is not, really, true that they make some kind of
: self/non-self decision at this point. However, I see that I may be
: straying into semantics (not my original intention, I assure you.) Other
: systems can make a self/non-self decision for the macrophage. For
: example, things like complement systems activation, or antibody binding,
: reslting in opsinization; the presence of bacterial-type membranes (help
: me out here, somebody - I can't remember what it is in bacterial
: membranes hat makes them an opsinin) enhances uptake. BUT the crucial
: point is that macrophages DO present self antigen. And very
: efficiently. I inclded references on this in my previous post.
What I was trying to get across is that macrophages come across a variety
of antigens all the time. There MUST be some mechanism ( Could be very
simple) that will inform the macrophage about the origin of the antigen.
If a free flowing macrophage comes across a foreign antigen and lets say a
T cell, the latter will be ignored. But how does it know? Probably through
cell-cell contact. It would make a lot more sense to educate the
macrophages what a self antigen is ( which is of a LIMITED number) than
educate them what a foreign antigen is ( as the latter is infinite). If
you taught a cell all the possibilities of self antigens that it
might come across, then everything else would be considered foreign to it.
Shahram Mori _/\_
Program in Molecular Biology _\ /_ Saskatoon/SK/CANADA
Dept. of chemistry and Biochemistry Box 3C \_ _/
NMSU Las Cruces NM ||
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